Assume that Virgil purchases a combination of products Y and Z such that, after he is done spending his entire budget, MUy / Py = 25 and MUz / Pz = 25. Based on the equal marginal principle, Virgil
a. Should have purchased more Y and less Z.
b. Should have purchased less Y and more Z.
c. Should have purchased more Y and more Z.
d. Is maximizing his total utility.